Klaus Knopper is the creator of Knoppix and co-founder of the LinuxTag expo. He currently works as a teacher, programmer, and consultant. If you have a configuration problem, or if you just want to learn more about how Linux works, send your questions to: klaus@linux-magazine. com

Users log on to services such as SSH, ftp, SASL, POP3, IMAP, Apache htaccess, and many more using their names and passwords. These popular access mechanisms are a potential target for brute-force attacks. An attentive bouncer will keep dictionary attacks at bay.